Laser beams are generated by means of a population inversion consisting of an unstable abundance of molecules having excited high energy electronic states which release photons as they decay to the equilibrium lower energy states of the optically active media.
In high energy chemical lasers, the excited electronic states are generated by a chemical reaction. For example, one such reaction involves the use of excited molecular oxygen, hereinafter referred to as singlet delta oxygen (SDO) or O2(1Δ), in combination with an optically active media or lasing substance, such as iodine or fluorine.
One method presently in use for generating a stream of SDO involves a chemical reaction between chlorine gas and a basic solution of hydrogen peroxide, hereinafter referred to as basic hydrogen peroxide (BHP). The excited oxygen can then be added to a suitable lasing medium and the mixture passed through an optical resonator/cavity to bring about a lasing action.
These lasers have been found to be very useful but improved performance characteristics, especially in the area of materials supply and efficiency, is desirable. In particular, a number of problems in the supply, storage, and maintenance of the BHP reactant material has limited the use of these chemical lasers in military and airborne applications.
A high-performance tactical laser weapon requires a laser that operates on a sustained basis, providing rapid fire capability. Many lasers, such as chemical oxygen iodine lasers (COILs) (e.g., the Advanced Tactical Laser (ATL) Advanced Component Technology Demonstration (ACTD)), can operate only in a short lasing burst limited by the supply of BHP. Each burst is separated by a longer time period during which spent and excess BHP is recycled to support another lasing burst. This limits the utility of laser weapons and hence their potential.
In both the ATL and the airborne laser (ABL), the BHP is reacted as finely divided high-velocity jets or droplets with a low pressure chlorine stream. Current technology to provide continuous BHP circulation and lasing, e.g., the approach taken for ABL, takes advantage of the large, high interior of the Boeing 747 aircraft to meet this need. The liquid is separated from the low pressure product gas stream and coalesced into a largely gas-free stream suitable for reuse through centrifugal separators. These centrifugal separators are large, heavy, and utilize the height of the aircraft to gravitationally counteract viscous losses to prevent cavitation at the low pressures of the laser. Such a system and method are not adaptable to tactical platforms that are both much smaller and flatter.
The flow conditions at the location on the COIL device at which the BHP jets or droplets exit present conditions that are far outside of the conditions encountered in typical industrial phase separations, including distillation and gas/liquid separation or demisting. In comparison to distillation, the average liquid loading for laser usage is approximately 100 times that typically encountered, and peak locations have loadings of 1,000 times or higher than typically encountered in industrial applications. The liquid-to-gas weight ratio is also unusually high, running upwards of 10,000 compared to normal industrial distillation conditions of 10 or less. In industrial demisting applications, the liquid-to-gas weight ratio is even lower, typically 0.1 or lower.
Thus, no industrial technology is known that meets the flow control and gas/liquid separation requirements for laser applications. Accordingly, an apparatus and method for gas/liquid separation for laser applications adaptable to relatively smaller and flatter platforms are highly desirable.